VertaMax 3000 Problems.

I have a Vmax 3000-12p thats 2.5 years old
It started not producing electric to the circuit recently and seems to be getting worse. When turned on it sounds like it normally does on start up and even shows a green function light and the battery charge. Just no AC out. I have it wired direct to our breaker box in our cabin. Often if I turn on our generator for a while and then turn it off the inverter seems to be working fine. It's not worked hard, I've never had the fan come on. If we have a heavy load or batteries are low, we just use our generator. Seems like I've got a switch going bad. Any ideas? Also where can I get a schematic for the inverter.